Complement Pathway Inhibitors Binding To C5 And C5a Without Preventing The Formation Of C5b

ABSTRACT

The invention relates to inhibitors that bind to C5 and C5a, but which do not prevent the activation of C5 and do not prevent formation of or inhibit the activity of C5b. One example of such an inhibitor molecule is the monoclonal antibody designated MAb137-26, which binds to a shared epitope of human C5 and C5a. These inhibitors may be used to inhibit the activity of C5a in treating diseases and conditions mediated by excessive or uncontrolled production of C5a. The inhibitor molecules are also useful for diagnostic detection of the presence/absence or amount of C5 or C5a.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/011,058 filed Jan. 24, 2008, which is a continuation of U.S.application Ser. No. 10/222,464 filed Aug. 17, 2002, now U.S. Pat. No.7,432,356, which claims priority to U.S. provisional application No.60/313,137 filed Aug. 17, 2001, the disclosure of each of which isincorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to inflammation inhibitors which bind tocomplement C5 and C5a without inhibiting the formation of C5b and C5b-9membrane attack complexes (MAC).

BACKGROUND OF THE INVENTION

The complement system plays a central role in the clearance of immunecomplexes and in immune responses to infectious agents, foreignantigens, virus-infected cells and tumor cells. However, inappropriateor excessive activation of the complement system can lead to harmful,and even potentially life-threatening, consequences due to severeinflammation and resulting tissue destruction. These consequences areclinically manifested in various disorders including septic shock,myocardial as well as intestinal ischemia/reperfusion injury, graftrejection, organ failure, nephritis, pathological inflammation andautoimmune diseases. Sepsis, for example, is a major cause of mortalityresulting in over 200,000 deaths per year in the United States alone.Despite the major advances in the past several years in the treatment ofserious infections, the incidence and mortality from sepsis continues torise. Therefore, inhibition of excessive or uncontrolled activation ofthe complement cascade could provide clinical benefit to patients withsuch diseases and conditions.

The complement system is composed of a group of proteins that arenormally present in the serum in an inactive state. Activation of thecomplement system encompasses mainly two distinct pathways, designatedthe classical and the alternative pathways (V. M. Holers, In ClinicalImmunology: Principles and Practice, ed. R. R. Rich, Mosby Press; 1996,363-391). The classical pathway is a calcium/magnesium-dependentcascade, which is normally activated by the formation ofantigen-antibody complexes. It can also be activated in anantibody-independent manner by the binding of C-reactive protein,complexed with ligand, and by many pathogens including gram-negativebacteria. The alternative pathway is a magnesium-dependent cascade whichis activated by deposition and activation of C3 on certain susceptiblesurfaces (e.g. cell wall polysaccharides of yeast and bacteria, andcertain biopolymer materials).

Recent studies have shown that complement can also be activated throughthe lectin pathway, which involves the initial binding ofmannose-binding lectin and the subsequent activation of C2 and C4, whichare common to the classical pathway (Matsushita, M. et al., J. Exp. Med.176: 1497-1502 (1992); Suankratay, C. et al., J. Immunol. 160: 3006-3013(1998)). Accumulating evidence indicates that the alternative pathwayparticipates in the amplification of the activity of both the classicalpathway and the lectin pathway (Suankratay, C., ibid; Farries, T. C. etal., Mol. Immunol. 27: 1155-1161 (1990)). Activation of the complementpathway generates biologically active fragments of complement proteins,e.g. C3a, C4a and C5a anaphylatoxins and C5b-9 membrane attack complexes(MAC), which mediate inflammatory responses through involvement ofleukocyte chemotaxis, activation of macrophages, neutrophils, platelets,mast cells and endothelial cells, increased vascular permeability,cytolysis, and tissue injury.

Complement C5a is one of the most potent proinflammatory mediators ofthe complement system. C5a is the activated form of C5. Complement C5(190 kD, molecular weight) is present in human serum at approximately 80pig/ml (Kohler, P. F. et al., J. Immunol. 99: 1211-1216 (1967)). It iscomposed of two polypeptide chains, α and β, with approximate molecularweights of 115 kD and 75 kD, respectively (Tack, B. F. et al.,Biochemistry 18: 1490-1497 (1979)). Biosynthesized as a single-chainpromolecule, C5 is enzymatically cleaved into a two-chain structureduring processing and secretion. After cleavage, the two chains are heldtogether by at least one disulphide bond as well as noncovalentinteractions (Ooi, Y. M. et al., J. Immunol. 124: 2494-2498 (1980)).

Primary amino acid structures of human and murine C5 were obtained fromcDNA sequencing data (Wetsel, R A. et al., Biochemistry 27: 1474-1482(1988); Haviland, D. L. et al., J. Immunol. 146: 362-368 (1991): Wetsel,R A. et al., Biochemistry 26: 737-743 (1987)). The deduced amino acidsequence of precursor human pre-pro-C5 has 1676 amino acids. The α- andβ-chains of mature C5 have 999 and 655 amino acids, respectively. C5 isglycosylated in the C5 α-chain, in particular the asparagine at residue64.

C5 is cleaved into the C5a and C5b fragments during activation of thecomplement pathways. The convertase enzymes responsible for C5activation are multi-subunit complexes of C4b, C2a, and C3b for theclassical pathway and of (C3b)₂, Bb, and P for the alternative pathway(Goldlust, M. B. et al., J. Immunol. 113: 998-1007 (1974); Schreiber, RD. et al., Proc. Natl. Acad. Sci. 75: 3948-3952 (1978)). C5 is activatedby cleavage at position 74-75 (Arg-Leu) in the α-chain. Afteractivation, the 11.2 kD, 74 amino acid peptide C5a from theamino-terminus portion of the α-chain is released. This C5a peptideshares similar anaphylatoxin properties with those exhibited by C3a, butis 100 times more potent, on a molar basis, in eliciting inflammatoryresponses. Both C5a and C3a are potent stimulators of neutrophils andmonocytes (Schindler, R. et al., Blood 76: 1631-1638 (1990);Haeffner-Cavaillon, N. et al., J. Immunol. 138: 794-700 (1987);Cavaillon, J. M. et al., Eur. J. Immunol. 20: 253-257 (1990)).Furthermore, C3a receptor was recently shown to be important forprotection against endotoxin-induced shock in a mouse model (Kildsgaard,J. et al., J. Immunol. 165: 5406-5409 (2000)).

In addition to its anaphylatoxic properties, C5a induces chemotacticmigration of neutrophils (Ward, P. A. et al., J. Immunol. 102: 93-99(1969)), eosinophils (Kay, A. B. et al., Immunol. 24: 969-976 (1973)),basophils (Lett-Brown, M. A. et al., J. Immunol. 117: 246-252 1976)),and monocytes (Snyderman, R. et al., Proc. Soc. Exp. Biol. Med. 138:387-390 1971)). The activity of C5a is regulated by the plasma enzymecarboxypeptidase N (E.C. 3.4.12.7) that removes the carboxy-terminalarginine from C5a forming the C5a des Arg derivative (Goetzl, E. J. etal., J. Clin. Invest. 53: 591-599 (1974)). On a molar basis, human G5ades Arg exhibits only 1% of the anaphylactic activity (Gerard, C. etal., Proc. Natl. Acad. Sci. 78: 1833-1837 (1981)) and polymorphonuclearchemotactic activity as unmodified C5a (Chenoweth, D. E. et al., Mol.Immunol. 17: 151-161 (1980)). Both C5a and C5b-9 activate endothelialcells to express adhesion molecules essential for sequestration ofactivated leukocytes, which mediate tissue inflammation and injury(Foreman, K. E. et al., J. Clin. Invest. 94: 1147-1155 (1994); Foreman,K. E. et al., Inflammation 20: 1-9 (1996); Rollins, S. A. et al.,Transplantation 69: 1959-1967 (2000)). C5a also mediates inflammatoryreactions by causing smooth muscle contraction, increasing vascularpermeability, inducing basophil and mast cell degranulation and inducingrelease of lysosomal proteases and oxidative free radicals (Gerard, C.et al., Ann. Rev. Immunol. 12: 775-808 (1994)). Furthermore, C5amodulates the hepatic acute-phase gene expression and augments theoverall immune response by increasing the production of TNFα. IL-1β,IL-6, and IL-8 (Lambris, J. D. et al., In: The Human Complement Systemin Health and Disease, Volanakis, J. E. ed., Marcel Dekker, New York,pp. 83-118).

The human C5a receptor (C5aR) has been cloned (Gerard, N. P. et al.,Nature 349: 614-617 (1991); Boulay, F. et al., Biochemistry 30:2993-2999 (1991)). It belongs to a superfamily ofseven-transmembrane-domain, G protein-coupled receptors. C5aR isexpressed on neutrophils, monocytes, basophils, eosinophils,hepatocytes, lung smooth muscle and endothelial cells, and renalglomerular tissues (Van-Epps, D. E. et al., J. Immunol. 132: 2862-2867(1984); Haviland, D. L. et al., J. Immunol. 154:1861-1869 (1995);Wetsel, R. A., Immunol. Lett. 44: 183-187 (1995); Buchner, R. R. et al.,J. Immunol. 155: 308-315 (1995); Chenoweth, D. E. et al., Proc. Natl.Acad. Sci. 75: 3943-3947 (1978); Zwirner, J. et al., Mol. Immunol.36:877-884 (1999)). The ligand-binding site of C5aR is complex andconsists of at least two physically separable binding domains. One bindsthe C5a amino terminus (amino acids 1-20) and disulfide-linked core(amino acids 21-61), while the second binds the C5a carboxy-terminal end(amino acids 62-74) (Wetsel, R A., Curr. Opin. Immunol. 7: 48-53(1995)).

C5a plays important roles in inflammation and tissue injury. Incardiopulmonary bypass and hemodialysis, C5a is formed as a result ofactivation of the alternative complement pathway when human blood makescontact with the artificial surface of the heart-lung machine or kidneydialysis machine (Howard, R. J. et al., Arch. Surg. 123: 1496-1501(1988); Kirklin, J. K. et al., J. Cardiovasc. Surg. 86: 845-857 (1983);Craddock, P. R. et al., N. Engl. J. Med. 296: 769-774 (1977)). C5acauses increased capillary permeability and edema, bronchoconstriction,pulmonary vasoconstriction, leukocyte and platelet activation andinfiltration to tissues, in particular the lung (Czermak, B. J. et al.,J. Leukoc. Biol. 64: 40-48 (1998)). Administration of an anti-C5amonoclonal antibody was shown to reduce cardiopulmonary bypass andcardioplegia-induced coronary endothelial dysfunction (Tofukuji, M. etal., J. Thorac. Cardiovasc. Surg. 116: 1060-1068 (1998)).

C5a is also involved in acute respiratory distress syndrome (ARDS) andmultiple organ failure (MOF) (Hack, C. E. et al., Am. J. Med. 1989: 86:20-26; Hammerschmidt D E et al. Lancet 1980; 1: 947-949; Heideman M. etal. J. Trauma 1984; 4: 1038-1043). C5a augments monocyte production oftwo important pro-inflammatory cytokines, TNFα and IL-1. C5a has alsobeen shown to play an important role in the development of tissueinjury, and particularly pulmonary injury, in animal models of septicshock. (Smedegard G et al. Am. J. Pathol. 1989; 135: 489-497). In sepsismodels using rats, pigs and non-human primates, anti-C5a antibodiesadministered to the animals before treatment with endotoxin or E. coliresulted in decreased tissue injury, as well as decreased production ofIL-6 (Smedegard, G. et al., Am. J. Pathol. 135: 489-497 (1989); Hopken,U. et al., Eur. J. Immunol. 26: 1103-1109 (1996); Stevens, J. H. et al.,J. Clin. Invest. 77: 1812-1816 (1986)). More importantly, blockade ofC5a with anti-C5a polyclonal antibodies has been shown to significantlyimprove survival rates in a caecal ligation/puncture model of sepsis inrats (Czermak, B. J. et al., Nat. Med. 5: 788-792 (1999)). This modelshares many aspects of the clinical manifestation of sepsis in humans.(Parker, S. J. et al., Br. J. Surg. 88: 22-30 (2001)). In the samesepsis model, anti-C5a antibodies were shown to inhibit apoptosis ofthymocytes (Guo, R. F. et al., J. Clin. Invest. 106: 1271-1280 2000))and prevent MOF (Huber-Lang, M. et al., J. Immunol. 166: 1193-1199(2001)). Anti-C5a antibodies were also protective in a cobra venomfactor model of lung injury in rats, and in immune complex-induced lunginjury (Mulligan, M. S. et al. J. Clin. Invest. 98: 503-512 (1996)). Theimportance of C5a in immune complex-mediated lung injury was laterconfirmed in mice (Bozic, C. R. et al., Science 26: 1103-1109 (1996)).

C5a is found to be a major mediator in myocardial ischemia-reperfusioninjury. Complement depletion reduced myocardial infarct size in mice(Weisman, H. F. et al., Science 249: 146-151 (1990)), and treatment withanti-C5a antibodies reduced injury in a rat model of hindlimbischemia-reperfusion (Bless, N. M. et al., Am. J. Physiol. 276: L57-L63(1999)). Reperfusion injury during myocardial infarction was alsomarkedly reduced in pigs that were retreated with a monoclonal anti-C5aIgG (Amsterdam, E. A. et al., Am. J. Physiol. 268:H448-H457 (1995)). Arecombinant human C5aR antagonist reduces infarct size in a porcinemodel of surgical revascularization (Riley, R D. et al., J. Thorac.Cardiovasc. Surg. 120: 350-358 (2000)).

Complement levels are elevated in patients with rheumatoid arthritis andsystemic lupus erythematosus. C5a levels correlate with the severity ofthe disease state (Jose, P. J. et al., Ann. Rheum. Dis. 49: 747-752(1989); Porcel, J. M. et al., Clin. Immunol. Immunopathol. 74: 283-288(1995)). Therefore, inhibition of C5a and/or C5a receptor (C5aR) couldbe useful in treating these chronic diseases.

C5aR expression is upregulated on reactive astrocytes, microglia, andendothelial cells in an inflamed human central nervous system (Gasque,P. et al., Am. J. Pathol. 150: 31-41 (1997)). G5a might be involved inneurodegenerative diseases, such as Alzheimer disease (Mukherjee, P. etal., J. Neuroimmunol. 105: 124-130 (2000)). Activation of neuronal C5aRmay induce apoptosis (Farkas I et al. J. Physiol. 1998: 507: 679-687).Therefore, inhibition of C5a and/or C5aR could also be useful intreating neurodegenerative diseases.

Psoriasis is now known to be a T cell-mediated disease (Gottlieb, E. L.et al., Nat. Med. 1: 442-447 (1995)). However, neutrophils and mastcells may also be involved in the pathogenesis of the disease (Terui, T.et al., Exp. Dermatol. 9: 1-10; 2000); Werfel, T. et al., Arch.Dermatol. Res. 289: 83-86 (1997)). High levels of C5a des Arg are foundin psoriatic scales, indicating that complement activation is involved.T cells and neutrophils are chemo-attracted by C5a (Nataf, S. et al., J.Immunol. 162: 4018-4023 (1999); Tsuji, R. F. et al., J. Immunol. 165:1588-1598 (2000); Cavaillon, J. M. et al., Eur. J. Immunol. 20: 253-257(1990)). Therefore C5a could be an important therapeutic target fortreatment of psoriasis.

Immunoglobulin G-containing immune complexes (IC) contribute to thepathophysiology in a number of autoimmune diseases, such as systemiclupus erthyematosus, rheumatoid arthritis, Goodpasture's syndrome, andhypersensitivity pneumonitis (Madaio, M. P., Semin. Nephrol. 19: 48-56(1999); Korganow, A. S. et al., Immunity 10: 451-459 (1999); Bolten, W.K., Kidney Int. 50: 1754-1760 (1996); Ando, M. et al., Curr. Opin. Pulm.Med. 3: 391-399 (1997)). The classical animal model for the inflammatoryresponse in these IC diseases is the Arthus reaction, which features theinfiltration of polymorphonuclear cells, hemorrhage, and plasmaexudation (Arthus, M., C. R. Soc. Biol. 55: 817-824 (1903)). Recentstudies show that C5aR deficient mice are protected from tissue injuryinduced by IC (Kohl, J. et al., Mol. Immunol. 36: 893-903 (1999);Baumann, U. et al., J. Immunol. 164: 1065-1070 (2000)). The results areconsistent with the observation that a small peptidic anti-C5aRantagonist inhibits the inflammatory response caused by IC deposition(Strachan, A. J. et al., J. Immunol. 164: 6560-6565 (2000)). Togetherwith its receptor, C5a plays an important role in the pathogenesis of ICdiseases. Inhibitors of C5a and C5aR could be useful to treat thesediseases.

WO01/15731A1 discusses compositions and methods of treatment of sepsisusing antibodies to C5a. These antibodies react only with the N-terminalregion of the C5a peptide and do not cross-react with C5.

WO86/05692 discusses the treatment of adult respiratory distresssyndrome (ARDS) with an antibody specific for C5a or the des Argderivative thereof. It also discloses the treatment of sepsis byadministering this antibody. This antibody was produced in response tothe C5a des Arg derivative because it is more immunogenic, but willelicit antibodies cross reactive with C5a. U.S. Pat. No. 5,853,722discusses anti-C5 antibodies that block the activation of C5 and thus,the formation of C5a and C5b.

U.S. Pat. No. 6,074,642 discusses the use of anti-C5 antibodies to treatglomerulonephritis. These antibodies also block the generation of C5aand C5b, inhibiting the effect of both C5a and the formation of C5b-9.U.S. Pat. No. 5,562,904 discusses anti-C5 antibodies that completelyblock the formation of MAC.

In other discussions of anti-C5 antibodies, the antibodies disclosedblock activation of C5 and its cleavage to form C5a and C5b (Vakeva, A.P. et al., Circulation 97:2259-2267 (1998); Thomas, T. C. et al., Mol.Immunol. 33:1389-1401 (1996); Wang, Y. et al., Proc Natl Acad Sci.93:8563-8568 (1996); Kroshus, T. et al., Transplantation 60:1194-1202(1995); Frei, Y. et al., Mol. Cell Probes 1:141-149 (1987)).

Monoclonal antibodies cross-reactive with C5, C5a, or C5a des Arg havebeen reported (Schulze, M. et al., Complement 3: 25-39 (1986); Takeda,J. et al., J. Immunol. Meth. 101: 265-270 (1987); Inoue, K., ComplementInflamm. 6: 219-222 (1989). It has also been reported that monoclonalantibodies cross-reactive with C5 and C5a inhibited C5a-mediated ATPrelease from guinea pig platelets (Klos, A. et al., J. Immunol. Meth.111: 241-252 (1988); Oppermann, M. et al., Complement Inflamm. 8: 13-24(1991)).

SUMMARY OF THE INVENTION

C5 activation normally results in cleavage of C5 to C5a and C5b. Theinhibitor molecules of the present invention bind to C5 and C5a withhigh affinity, do not inhibit C5 activation, and do not prevent theformation of or inhibit the activity of C5b. One example of such aninhibitor is the monoclonal antibody designated MAb 137-26, which bindsto a shared epitope on human C5 and C5a. The hybridoma that produces themonoclonal antibody 137-26 has been deposited at the American TypeCulture Collection, 10801 University Blvd., Manassas, Va. 20110-2209,under Accession No. PTA-3650 on Aug. 17, 2001.

The inhibitor molecules of the invention also include: (i) otherantibodies or fragments thereof, peptides, oligonucleotides, orpeptidomimetics that bind to C5 and C5a with high affinity, but do notinhibit C5 activation, and do not prevent the formation of or inhibitthe activity of C5b, or (ii) any antibody that binds to the same epitopeas the monoclonal antibody 137-26. Antibody fragments include Fab,F(ab′)₂, Fv, or single chain Fv, and monoclonal antibodies and fragmentsof the invention include chimeric, deimmunized, humanized or humanantibodies and fragments, and other forms acceptable for human use. Theinhibitor molecules may be included as part of a pharmaceuticalcomposition.

The inhibitor molecules of the invention are useful for treatment ofdiseases and conditions involving excessive or uncontrolled productionof C5a, or for diagnostic use in detecting the presence of, orquantitation, C5a.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the binding of MAb 137-26 (anti-C5a, closed squares) andMAb 137-76 (anti-C5 β-chain, open circles) to purified human C5a inELISA. An isotype-matched irrelevant monoclonal antibody was used asnegative control. The Y-axis represents the reactivity of the MAbs withC5a expressed as optical density (OD) at 450 nm and the X-axisrepresents the concentration of the MAbs. MAb 137-26 reacted with humanC5a, whereas MAb 137-76 and the irrelevant control antibody did not.

FIG. 2 shows the binding of MAb 137-26 (closed squares) and MAb 137-76(open circles) to purified human C5 in ELISA. An isotype-matchedirrelevant monoclonal antibody was used as negative control. The Y-axisrepresents the reactivity of the MAbs with C5 expressed as opticaldensity (OD) at 450 nm and the X-axis represents the concentration ofthe monoclonal antibodies. Both MAb 137-26 and MAb 137-76 reacted withhuman C5, whereas the irrelevant antibody did not.

FIG. 3 shows the inability of anti-C5a MAb 137-26 to inhibitcomplement-mediated hemolysis of sensitized chicken red blood cells viathe classical pathway (CP). Anti-C2 MAb 175-62 effectively inhibited thehemolysis. An isotype-matched irrelevant monoclonal antibody had noeffect. The Y-axis represents the percentage of hemolysis inhibition, asfurther described in the text. The X-axis represents the concentrationof the monoclonal antibodies.

FIG. 4 shows the inability of anti-C5a MAb 137-26 to inhibitcomplement-mediated hemolysis of rabbit red blood cells via thealternative pathway (AP). Anti-factor D MAb 166-32 effectively inhibitedthe hemolysis. An isotype-matched irrelevant monoclonal antibody had noeffect. The Y-axis represents the percentage hemolysis inhibition, asfurther described in the text. The X-axis represents the concentrationof monoclonal antibodies.

FIG. 5 shows the inhibition of the binding of radioiodinated(¹²⁵I)-human C5a to purified human neutrophils. The positive control,purified recombinant human C5a (rHuC5a), inhibited the binding. Anisotype-matched irrelevant monoclonal antibody did not show any effect.The Y-axis represents the percentage inhibition of ¹²⁵I-C5a binding, asfurther described in the text. The X-axis represents the concentrationof the competing agents.

FIG. 6 shows the binding epitope of MAb 137-26 on human C5a mapped byoverlapping synthetic peptides on cellulose membrane.

FIG. 7A shows CD11b expression on human neutrophils stimulated byopsonized E. coli in a lepirudin anti-coagulated whole blood model.Anti-C5/C5a MAb137-26 (closed circles) inhibited CD11b expression moreeffectively than anti-C5a MAb561 (Dr. Jurg Kohl, closed squares) andanti-C5 MAb137-30 (closed triangles). The latter antibody inhibited C5activation. The irrelevant MAb (closed inverted triangles) had noeffect. The Y-axis represents mean fluorescence intensity (MFI) measuredby immunofluorocytometry. The X-axis represents the concentration of theantibodies (μg/ml) T−0=baseline whole blood sample at time 0 min.T−10=whole blood incubated only with PBS for 10 min without E. coli.Other samples, with or without inhibitors, had E. coli added.

FIG. 7B shows CD11b expression on human neutrophils stimulated byopsonized E. coli in a lepirudin anti-coagulated whole blood model.Anti-C5/C5a MAb 137-26 (closed circles) inhibited CD11b expression moreeffectively than a peptidic C5aR antagonist (Dr. Stephen Taylor) (closedsquares). The irrelevant peptide had no effect (closed invertedtriangles). The Y-axis represents mean fluorescence intensity (MFI)measured by immunofluorocytometry. The X-axis represents theconcentration of the antibodies/peptide (μg/ml). T−0=baseline wholeblood sample at time 0 min. T−10=whole blood incubated only with PBS for10 min without E. coli. Other samples, with or without inhibitors, hadE. coli added.

FIG. 7C shows oxidative burst of human neutrophils stimulated byopsonized E. coli in a lepirudin anti-coagulated whole blood model. Bothanti-C5/C5a MAb137-26 (closed circles) and anti-C5 MAb137-30 (closedtriangles) inhibited oxidative burst more effectively than anti-C5aMAb561 (closed squares). The irrelevant antibody (closed invertedtriangles) had no effect. The Y-axis represents mean fluorescenceintensity (MFI) measured by immunofluorocytometry. The X-axis representsthe concentration of the antibodies (μg/ml). T−0=baseline whole bloodsample at time 0 min. T−10 whole blood incubated only with PBS for 10min without E. coli. Other samples, with or without inhibitors, had E.coli added.

FIG. 7D shows oxidative burst of human neutrophils stimulated byopsonized E. coli in a lepirudin anti-coagulated whole blood model.Anti-C5/C5a MAb137-26 was more effective than a peptidic C5aR antagonist(closed square) in inhibiting oxidative burst. The irrelevant peptidehad no effect. The Y-axis represents mean fluorescence intensity (MFI)measured by immunofluorocytometry. The X-axis represents theconcentration of the antibodies in nM. T−0=baseline whole blood sampleat time 0 min. T−10=whole blood incubated only with PBS for 10 minwithout E. coli. Other samples, with or without inhibitors, had E. coliadded.

FIG. 8 shows the MAC-mediated killing of Neisseria meningitides in alepirudin anti-coagulated whole blood model. The bacteria wereeffectively killed by incubation with the human whole blood in thepresence of anti-C5/C5a MAb137-26 (closed circles), an irrelevant MAb(closed triangles), or PBS (open squares). In contrast, the bacteriawere not killed when the whole blood was treated with anti-C5 MAb137-30(open diamonds) which inhibited C5 activation and thus MAC formation.The Y-axis represents colony forming units (CFU) per 100 μl of wholeblood incubated for 24 hours at 37° C. on blood agar. The X-axisrepresents different time points of blood sample collection from thewhole blood culture experiment.

DETAILED DESCRIPTION 1. Advantages of the Invention

The inhibitors of the invention, including monoclonal antibodyMAb137-26, are advantageous over known monoclonal antibody inhibitorsfor treating complement-mediated inflammation and tissue damage. MAb137-26 is capable of binding to C5 before it is activated. After C5 isactivated to form C5a, the antibody can neutralize C5a, which is ananaphylatoxin. Normally, once C5a is formed, it rapidly binds to C5aR oncells, thereby triggering the signal transduction cascade leading toinflammation. MAb137-26 does not inhibit the cleavage of C5 to form C5aand C5b, but C5a remains bound to MAb137-26 after it is produced, andinhibits binding of C5a to C5aR. The formation of C5b-9, however, is notaffected, and, inasmuch as C5b-9 is needed for MAC formation, which isinvolved in killing bacteria, maintaining production of C5b-9 isimportant for a protective immune response.

MAb 137-26 can effectively neutralize the inflammatory effects of C5a,but still allow other components of the complement cascade, including C3and C5b-9, to mediate anti-bacterial functions. This pharmacologicalproperty is exceptionally important with respect to the treatment ofbacterial sepsis, chronic IC diseases, and psoriasis.

2. Making and Using the Invention

A. Monoclonal Antibodies

Monoclonal antibodies may be made using the hybridoma method firstdescribed by Kohler et al., Nature, 256:495 (1975), or may be made byrecombinant DNA methods (U.S. Pat. No. 4,816,567).

In the hybridoma method, a mouse or other appropriate host animal isimmunized as hereinabove described to elicit lymphocytes that produce orare capable of producing antibodies that will specifically bind to theprotein used for immunization. Animals can also be immunized with DNAconstructs to express the encoding proteins in vivo for inducingspecific antibodies.

Alternatively, lymphocytes may be immunized in vitro. Lymphocytes thenare fused with myeloma cells using a suitable fusing agent, such aspolyethylene glycol, to form a hybridoma cell (Goding, MonoclonalAntibodies: Principles and Practice, pp. 59-103 (Academic Press, 1986)).

The hybridoma cells thus prepared are seeded and grown in a suitableculture medium that preferably contains one or more substances thatinhibit the growth or survival of the unfused, parental myeloma cells.For example, if the parental myeloma cells lack the enzyme hypoxanthineguanine phosphoribosyl transferase (HGPRT or HPRT), the culture mediumfor the hybridomas typically will include hypoxanthine, aminopterin, andthymidine (HAT medium), which substances prevent the growth ofHGPRT-deficient cells.

Preferred myeloma cells are those that fuse efficiently, support stablehigh-level production of antibody by the selected antibody-producingcells, and are sensitive to a medium such as HAT medium. Among thesemyeloma cell lines are murine myeloma lines, such as those derived fromMOPC-21 and MPC-11 mouse tumors available from the Salk Institute CellDistribution Center, San Diego, Calif. USA, and SP2/0 or X63-Ag8-653cells available from the American Type Culture Collection, Rockville,Md. USA. Human myeloma and mouse-human heteromyeloma cell lines alsohave been described for the production of human monoclonal antibodies(Kozbor, J. Immunol. 133:3001 (1984); Brodeur et al., MonoclonalAntibody Production Techniques and Applications, pp. 51-63 (MarcelDekker, Inc., New York, 1987)). The mouse myeloma cell line NS0 may alsobe used (European Collection of Cell Cultures, Salisbury, Wiltshire UK).

Culture medium in which hybridoma cells are grown is assayed forproduction of monoclonal antibodies directed against the antigen. Thebinding specificity of monoclonal antibodies produced by hybridoma cellsmay be determined by immunoprecipitation or by an in vitro bindingassay, such as radioimmunoassay (RIA) or enzyme-linked immunoabsorbentassay (ELISA).

After hybridoma cells are identified that produce antibodies of thedesired specificity, affinity, and/or activity, the clones may besubcloned by limiting dilution procedures and grown by standard methods(Goding, Monoclonal Antibodies: Principles and Practice, pp. 59-103(Academic Press, 1986)). Suitable culture media for this purposeinclude, for example, D-MEM or RPMI-1640 medium. In addition, thehybridoma cells may be grown in vivo as ascites tumors in an animal.

The monoclonal antibodies secreted by the subclones are suitablyseparated from the culture medium, ascites fluid, or serum byconventional immunoglobulin purification procedures such as, forexample, protein A-Sepharose*, hydroxylapatite chromatography, gelelectrophoresis, dialysis, or affinity chromatography.

DNA encoding the monoclonal antibodies is readily isolated and sequencedusing conventional procedures (Innis M. et al. In PCR Protocols. A Guideto Methods and Applications, Academic, San Diego, Calif. (1990), Sanger,F. S., et al. Proc. Nat. Acad. Sci. 74:5463-5467 (1977)). The hybridomacells serve as a source of such DNA. Once isolated, the DNA may beplaced into expression vectors, which are then transfected into hostcells such as E. coli cells, simian COS cells. Chinese hamster ovary(CHO) cells, or myeloma cells that do not otherwise produceimmunoglobulin protein, to obtain the synthesis of monoclonal antibodiesin the recombinant host cells. Recombinant production of antibodies willbe described in more detail below.

In a further embodiment, antibodies or antibody fragments can beisolated from antibody phage libraries generated using the techniquesdescribed in McCafferty. et al., Nature 348:552-554 (1990). Clackson, etal., Nature 352:624-628 (1991) and Marks, et al., J. Mol. Biol.222:581-597 (1991) describe the isolation of murine and humanantibodies, respectively, using phage libraries. Subsequent publicationsdescribe the production of high affinity (nM range) human antibodies bychain shuffling (Marks, et al., Bio/Technology 10:779-783 (1992)), aswell as combinatorial infection and in vivo recombination as a strategyfor constructing very large phage libraries (Waterhouse, et al., Nuc.Acids. Res. 21:2265-2266 (1993)). Thus, these techniques are viablealternatives to traditional monoclonal antibody hybridoma techniques forisolation of monoclonal antibodies.

The DNA also may be modified, for example, by substituting the codingsequence for human heavy- and light-chain constant domains in place ofthe homologous murine sequences (U.S. Pat. No. 4,816,567; Morrison, etal., Proc. Nat. Acad. Sci. USA 81:6851 (1984)), or by covalently joiningto the immunoglobulin coding sequence all or part of the coding sequencefor a non-immunoglobulin polypeptide.

Typically, such non-immunoglobulin polypeptides are substituted for theconstant domains of an antibody, or they are substituted for thevariable domains of one antigen-combining site of an antibody to createa chimeric bivalent antibody comprising one antigen-combining sitehaving specificity for an antigen and another antigen-combining sitehaving specificity for a different antigen.

Another alternative is to use electrical fusion rather than chemicalfusion to form hybridomas. This technique is well established. Insteadof fusion, one can also transform a B-cell to make it immortal using,for example, an Epstein Barr Virus, or a transforming gene. (See, e.g.,“Continuously Proliferating Human Cell Lines Synthesizing Antibody ofPredetermined Specificity,” Zurawaki, V. R. et al. in MonoclonalAntibodies, ed. by Kennett R. H. et al., Plenum Press, N.Y. 1980, pp19-33.)

B. Humanized and Human Antibodies

A humanized antibody has one or more amino acid residues introduced intoit from a source, which is non-human. These non-human amino acidresidues are often referred to as “import” residues, which are typicallytaken from an “import” variable domain. Humanization can be essentiallyperformed following the method of Winter and co-workers (Jones et al.,Nature 321:522-525 (1986); Riechmann et al., Nature 332:323-327 (1988);Verhoeyen, et al., Science, 239:1534-1536 (1988)), by substitutingrodent CDRs or CDR sequences for the corresponding sequences of a humanantibody. Accordingly, in such “humanized” antibodies, a substantiallyless than intact human variable domain has been substituted by thecorresponding sequence from a nonhuman species. In practice, humanizedantibodies are typically human antibodies in which some CDR residues andpossibly some FR residues are substituted by residues from analogoussites in rodent antibodies.

The choice of human variable domains, both light and heavy, to be usedin making the humanized antibodies is very important to reduceantigenicity. According to the so-called “best-fit” method, the sequenceof the variable domain of a rodent antibody is screened against theentire library of known human variable-domain sequences. The humansequence which is closest to that of the rodent is then accepted as thehuman framework (FR) for the humanized antibody (Sims et al., J.Immunol., 151:2296 (1993); Chothia et al., J. Mol. Biol., 196:901(1987)). Another method uses a particular framework derived from theconsensus sequence of all human antibodies of a particular subgroup oflight or heavy chains. The same framework may be used for severaldifferent humanized antibodies (Carter et al., Proc. Natl. Acad. Sci.USA, 89:4285 (1992); Presta et al., J. Immunol., 151:2623 (1993)).

It is further important that antibodies be humanized with retention ofhigh affinity for the antigen and other favorable biological properties.To achieve this goal, according to a preferred method, humanizedantibodies are prepared by a process of analysis of the parentalsequences and various conceptual humanized products usingthree-dimensional models of the parental and humanized sequences.Three-dimensional immunoglobulin models are commonly available and arefamiliar to those skilled in the art. Computer programs are availablewhich illustrate and display probable three-dimensional conformationalstructures of selected candidate immunoglobulin sequences. Inspection ofthese displays permits analysis of the likely role of the residues inthe functioning of the candidate immunoglobulin sequence, i.e., theanalysis of residues that influence the ability of the candidateimmunoglobulin to bind its antigen. In this way, FR residues can beselected and combined from the recipient and import sequences so thatthe desired antibody characteristic, such as increased affinity for thetarget antigen(s), is achieved. In general, the CDR residues aredirectly and most substantially involved in influencing antigen binding.

Alternatively, the skilled researcher can produce transgenic animals(e.g., mice) that are capable, upon immunization, of producing a fullrepertoire of human antibodies in the absence of endogenousimmunoglobulin production. Such transgenic mice are available fromAbgenix, Inc., Fremont, Calif., and Medarex, Inc., Annandale, N.J. Ithas been described that the homozygous deletion of the antibodyheavy-chain joining region (JH) gene in chimeric and germ-line mutantmice results in complete inhibition of endogenous antibody production.Transfer of the human germ-line immunoglobulin gene array in suchgerm-line mutant mice will result in the production of human antibodiesupon antigen challenge. See, e.g., Jakobovits et al., Proc. Natl. Acad.Sci. USA 90:2551 (1993); Jakobovits et al., Nature 362:255-258 (1993);Bruggermann et al., Year in Immunol. 7:33 (1993); and Duchosal et al.Nature 355:258 (1992). Human antibodies can also be derived fromphage-display libraries (Hoogenboom et al., J. Mol. Biol. 227:381(1991); Marks et al., J. Mol. Biol. 222:581-597 (1991); Vaughan, et al.,Nature Biotech 14:309 (1996)).

C. Deimmunized Antibodies

Deimmunized antibodies are antibodies in which the potential T cellepitopes have been eliminated, as described in International PatentApplication PCT/GB98/01473. Therefore, immunogenicity in humans isexpected to be eliminated or substantially reduced when they are appliedin vivo.

Additionally, antibodies can be chemically modified by covalentconjugation to a polymer to increase their circulating half-life, forexample. Preferred polymers, and methods to attach them to peptides, areshown in U.S. Pat. Nos. 4,766,106; 4,179,337; 4,495,285; and 4,609,546,which are all hereby incorporated by reference in their entireties.Preferred polymers are polyoxyethylated polyols and polyethylene glycol(PEG). PEG is soluble in water at room temperature and has a preferredaverage molecular weight between 1000 and 40,000, more preferablybetween 2000 and 20,000, most preferably between 3,000 and 12,000.

D. Generation of Anti-C5/C5a MAbs

Antibodies of the present invention may be generated by traditionalhybridoma techniques well known in the art. Briefly, mice are immunizedwith C5 purified from human sera as an immunogen emulsified in completeFreund's adjuvant, and injected subcutaneously or intraperitoneally inamounts ranging from 10-100 μg. Ten to fifteen days later, the immunizedanimals are boosted with additional C5 emulsified in incomplete Freund'sadjuvant. Mice are periodically boosted thereafter on a weekly tobi-weekly immunization schedule.

For each fusion, single cell suspensions were prepared from the spleenof an immunized mouse and used for fusion with SP2/0 myeloma cells.SP2/0 cells (1×10⁸) and spleen cells (1×10⁸) were fused in a mediumcontaining 50% polyethylene glycol (M.W. 1450) (Kodak, Rochester, N.Y.)and 5% dimethylsulfoxide (Sigma Chemical Co., St. Louis, Mo.). The cellswere then adjusted to a concentration of 1.7×10⁵ spleen cells/ml of thesuspension in DMEM medium (Gibco, Grand Island, N.Y.), supplemented with5% fetal bovine serum and HAT (10 mM sodium hypoxanthine, 40 μMaminopterin, and 1.6 mM thymidine). Two hundred and fifty microliters ofthe cell suspension were added to each well of about fifty 96-wellmicrotest plates. After about ten days culture supernatants werewithdrawn for screening for reactivity with purified human C5 by ELISA.

Wells of Immulon® II (Dynatech Laboratories, Chantilly, Va.) microtestplates were coated overnight with human C5 at 0.1 μg/ml (50 μl/well).The non-specific binding sites in the wells were then saturated byincubation with 200 μl of 5% BLOTTO (non-fat dry milk) inphosphate-buffered saline (PBS) for one hour. The wells were then washedwith PBST buffer (PBS containing 0.05% TWEEN® 20). Fifty microliters ofculture supernatant from each fusion well were added to the coated welltogether with 50 μl of BLOTTO for one hour at room temperature. Thewells were washed with PBST. The bound antibodies were then detected byreaction with diluted horseradish peroxidase (HRP) conjugated goatanti-mouse IgG (Fc specific) (Jackson ImmunoResearch Laboratories, WestGrove, Pa.) for one hour at room temperature. The wells were then washedwith PBST. Peroxidase substrate solution containing 0.1% 3,3,5,5,tetramethyl benzidine (Sigma, St. Louis, Mo.) and 0.003% hydrogenperoxide (Sigma, St. Louis, Mo.) in 0.1 M sodium acetate pH 6.0 wasadded to the wells for color development for 30 minutes. The reactionwas terminated by addition of 50 μl of 2M H₂SO₄ per well. The opticaldensity (00) was read at 450 nm with an ELISA reader (DynatechLaboratories, Chantilly, Va.).

Hybridomas in wells positive for C5 reactivity were single-cell clonedby a limiting dilution method. Monoclonal hybridomas were then expandedand culture supernatants collected for purification by protein Achromatography. The purified antibodies were then characterized forreactivity with human C5 and C5a by ELISA, for determination of affinityand kinetic binding constants by BIAcore, for effects oncomplement-mediated hemolysis via both the classical and the alternativepathways, and for inhibition of ¹²⁵I-C5a binding to purified humanneutrophils.

Antibodies may also be selected by panning a library of human scFv forthose which bind C5 (Griffiths et. al., EMBO J. 12:725-734 (1993)). Thespecificity and activity of specific clones can be assessed using knownassays (Griffiths et. al.; Clarkson et. al., Nature. 352: 642-648(1991)). After a first panning step, one obtains a library of phagecontaining a plurality of different single chain antibodies displayed onphage having improved binding for C5. Subsequent panning steps provideadditional libraries with higher binding affinities. When avidityeffects are a problem, monovalent phage display libraries may be used inwhich less than 20%, less than 10%, or less than 1% of the phage displaymore than one copy of an antibody on the surface of the phage.Monovalent display can be accomplished with the use of phagemid andhelper phage. Suitable phage include M13, fl and fd filamentous phage.Fusion protein display with virus coat proteins is also known and may beused in this invention.

MAb137-26, which binds both C5 and C5a with comparable affinity, wasfurther characterized. MAb 137-26 does not inhibit C5 activation, butinhibits with very high potency the binding of C5a to C5aR on purifiedhuman neutrophils. Experiments demonstrating these properties arefurther explained in the Examples below.

To screen for antibodies which bind to a particular epitope on theantigen of interest (e.g., those which block binding of any of theantibodies disclosed herein to C5), a routine cross-blocking assay suchas that described in Antibodies, A Laboratory Manual, Cold Spring HarborLaboratory, Ed Harlow and David Lane (1988), can be performed.Alternatively, epitope mapping, e.g. as described in Champe et al., J.Biol. Chem. 270:1388-1394 (1995), can be performed to determine whetherthe antibody binds an epitope of interest.

E. Making Other Inhibitors of the Invention

Other molecules suitable for use in the invention can be isolated orscreened from compound libraries by conventional means, for example, bydetermining whether they bind to C5/C5a, and then doing a functionalscreen to determine if they inhibit the activity of C5b. An automatedsystem for generating and screening a compound library is described inU.S. Pat. Nos. 5,901,069 and 5,463,564. More focused approaches involvea competitive screen against the MAb 137-26, or making athree-dimensional model of the binding site, and then making a family ofmolecules, which fit the model. These are then screened for those withoptimal binding characteristics. In addition, other molecules may beidentified by competition assay, or a functional screen for inhibitorswith the same properties as MAb137-26.

F. Using the Inhibitors of the Invention

The molecules of the present invention can be administered by any of anumber of routes and are administered at a concentration that istherapeutically effective in the indication or for the purpose sought.To accomplish this goal, the antibodies may be formulated using avariety of acceptable excipients known in the art. Typically, theantibodies are administered by injection. Methods to accomplish thisadministration are known to those of ordinary skill in the art. It mayalso be possible to obtain compositions which may be topically or orallyadministered, or which may be capable of transmission across mucousmembranes.

The dosage and mode of administration will depend on the individual andthe agent to be administered. The dosage can be determined by routineexperimentation in clinical trials or extrapolation from animal modelsin which the antibody was effective.

The antibodies of the present invention may be used in the treatment ofdiseases and conditions mediated by excessive or uncontrolled productionof C5a. Evidence of the utility of the inhibitors of the invention intreating these diseases and conditions is set forth below.

Example 1 Reactivity of MAb137-26 with Human C5 and C5a

MAb 137-26 was tested for reactivity with purified human C5 andrecombinant C5a (Sigma, St. Louis, Mo.). The procedures of the ELISA aredescribed above. MAb 137-26 binds to C5a in a dose-dependent manner withhigh potency (FIG. 1). Another anti-G5 MAb 137-76, specific for theβ-chain of human C5, does not bind C5a, because C5a resides on theα-chain of C5. An isotype-matched irrelevant antibody used as a negativecontrol also does not react with C5a. On the other hand, both MAbs137-26 and 137-76 bind to C5 (FIG. 2).

The affinity equilibrium constant and the binding kinetic constants(association and dissociation) of MAb 137-26 with C5a and C5 were alsodetermined by a BIAcore instrument (Pharmacia Biosensor AB. Uppsala,Sweden). All the binding measurements were performed in HEPES-bufferedsaline (HBS) (10 mM HEPES, pH 7.4, 150 mM NaCl, 3.4 mM EDTA, 0.005%Surfactant P20) at 25° C. To measure the binding rate constants of C5and C5a to MAb137-26, rabbit anti-mouse IgG(Fc) antibodies wereimmobilized onto a CM5 sensorchip by amine coupling usingN-hydroxysuccinimide and N-ethyl-N′-(3-diethylaminopropyl)cardodiimide.MAb 37-26 was then captured onto the coated sensorchip before theinjection of C5 at different concentrations. The data are summarized inTable 1. MAb137-26 has a high binding affinity for both solution-phaseC5a and G5. The results also indicate that MAb137-26 binds to an epitopeshared by both G5a and G5.

TABLE 1 Kinetic Constants of C5 and C5a Binding to MAb137-26 k_(on)k_(off) k_(D) (M⁻¹ s⁻¹) (S⁻¹) (M) C5 1.42 × 10⁵ 6.97 × 10⁻⁵ 4.92 × 10⁻¹⁰C5a  3.7 × 10⁶ 2.25 × 10⁻⁴ 6.09 × 10⁻¹¹ k_(on), kinetic associationconstant k_(off), kinetic dissociation constant k_(D), equilibriumdissociation constant = k_(off)/k_(on)

Example 2 Complement-Mediated Hemolysis

To study the effects of MAb 137-26 on the activation of C5 in humanserum, the antibody was tested for inhibition of hemolysis mediated bythe classical and the alternative complement pathways.

For the classical pathway experiments, chicken RBCs (5×10⁷ cells/ml) ingelatin/veronal buffered saline (GVB⁺⁺) containing 0.5 mM MgCI₂ and 0.15mM CaCI₂ were sensitized with purified rabbit anti-chicken RBCimmunoglobulins at 8 μg/ml (Inter-Cell Technologies, Hoperwell, N.J.)for 15 minutes at 4° C. The cells were then washed with GVB⁺⁺. Thewashed cells were re-suspended in the same buffer at 1.7×10⁸ cells/ml.In each well of a round-bottom 96-well microtest plate, 50 μl of normalhuman serum (5.2%) was mixed with 50 μl of GVB⁺⁺ of serially dilutedMAb137-26 or an anti-C2 MAb 175-62 as a positive control. Then 30 μl ofthe washed sensitized chicken RBCs suspension was added to the wellscontaining the mixtures. Fifty microliters of normal human serum (5.2%)was mixed with 80 μl of GVB⁺⁺ to give the serum color background. Anisotype-matched anti-HIV-1 gp120 MAb was used as negative control. Thefinal human serum concentration used was 2%. The mixture was incubatedat 37° C. for 30 minutes. The plate was shaken on a microtest plateshaker for 15 seconds. The plate was then centrifuged at 300×g for 3minutes. Supernatants (80 μl) were collected and transferred to wells ina flat-bottom 96-well microtest plates for measurement of OD at 405 nmby an ELISA plate reader. The percent inhibition of hemolysis is definedas:

100×[(OD_(without MAb)−OD_(serum color background))−(OD_(with MAb)−OD_(serum color background))]/(OD_(without MAb)−OD_(serum color background)).

FIG. 3 shows that MAb137-26 and the irrelevant control MAb G3-519 do notinhibit the classical pathway hemolysis of sensitized chicken RBCs,whereas the positive control, anti-C2 MAb 175-62, effectively inhibitshemolysis. C2 is specifically involved in the classical complementpathway.

For the alternative pathway, unsensitized rabbit RBCs were washed threetimes with gelatin/veronal-buffered saline (GVB/Mg-EGTA) containing 2 mMMgCI₂ and 1.6 mM EGTA. EGTA at a concentration of 10 mM was used toinhibit the classical pathway (K. Whaley et al., in A. W. Dodds (Ed.),Complement: A Practical Approach. Oxford University Press, Oxford, 1997,pp. 19-47). The assay procedures are similar to those of the classicalpathway hemolysis assay described above. The final concentration ofhuman serum used in the assay was 10%. Anti-factor D MAb 166-32 was usedas positive control. The same isotype-matched irrelevant anti-HIV-1gp120 MAb described above was used as negative control.

FIG. 4 shows that MAb137-26 does not inhibit the alternative pathwayhemolysis of unsensitized rabbit RBCs, whereas anti-factor D MAb166-32strongly inhibits the hemolysis. Factor D is specific for thealternative complement pathway. The negative control antibody has noeffect.

Taken together, the results verify that MAb 137-26 does not inhibit C5activation, and therefore the formation of C5a and C5b-9 are notinhibited. MAb137-26 does not inhibit the activation of the alternativeand classical complement pathways.

Example 3 Inhibition of ¹²⁵I-C5a Binding to Purified Human Neutrophilsby MAb 137-26

Human neutrophils were purified from human whole blood and diluted withDextran T−500/saline solution. The mixture was incubated at roomtemperature for about 20 minutes or until a clearly defined surfacelayer appeared. This surface layer was transferred to a 50-mlpolypropylene centrifuge tube. Following centrifugation, the cell pelletwas suspended in 30 ml of cold PBSB (1% BSA in PBS). The cell suspensionwas layered on top of 10 ml of Histopaque-1077 (Sigma, St. Louis, Mo.)in a 50-ml polypropylene centrifuge tube. Following anothercentrifugation, the cell pellet was then re-suspended in 20 ml of cold0.2% NaCl for 30 seconds to lyse RBCs. Then, 20 ml of cold 1.6% NaClwere added to the cell suspension, recentrifuged, and the neutrophilswere resuspended in PBSB. The neutrophils were kept on ice until beingused for ¹²⁵I-C5a binding.

MAb137-26 was serially diluted in 1.5 ml Eppendorf centrifuged tubeswith a binding buffer (1% BSA in RPMI1640 medium) to give finalconcentrations ranging from 640 nM to 0.04 nM. Four microliters of 4 nM¹²⁵I-C5a (NEN Life Science Products, Inc., Boston, Mass.) were added to36 μl of diluted MAb 137-26 for incubation at room temperature for 15minutes. Purified recombinant human C5a (Sigma, St. Louis, Mo. was usedas positive control, whereas an isotype-matched irrelevant monoclonalantibody was used as negative control. For the maximum binding of¹²⁵I-C5a, 36 μl of the binding buffer without the antibodies or C5a wasused instead. Fifty microliters of the neutrophil suspension was addedto each tube for incubation on ice. At the end of the 40-minuteincubation period, the mixture from each tube was transferred to the topof 800 μl of a separation buffer (6% BSA in PBS) in another Eppendorftube. The tubes were than centrifuged at 2000×g for 3 minutes at roomtemperature. After the supernatant was aspirated, the cell pellet wasre-suspended in 0.5 ml of de-ionized water to lyse the cells. The celllysate was then mixed with 3 ml of Ultima Gold scintillation fluid(Packard Instrument, Meriden, Conn.) for radioactive counting. Thepercent inhibition of ¹²⁵I-C5a binding is defined as:

[Cpm_(max)−Cpm_(bkg)]−[Cpm_(ca)−Cpm_(bkg)]/[Cpm_(max)−Cpm_(bkg)]×100

where:Cpm_(max)=maximum count per minute without competing agents;Cpm_(bkg)=background cpm without addition of ¹²⁵I-C5a; andCpm_(ca)=cpm with competing agents.

FIG. 5 shows the inhibition of the binding of radioiodinated(¹²⁵I)-human C5a to purified human neutrophils. MAb 137-26 is morepotent than unlabeled C5a in inhibiting the binding of ¹²⁵I-C5a topurified human neutrophils. The dose for 50% inhibition (ID50) for MAb137-26 was 0.45 nM as compared to 30 nM C5a.

Example 4 Mapping of the Binding Epitope of MAb137-26 on Human C5a bySPOTs Peptides on Cellulose Membrane

The binding epitope of MAb 137-26 on human C5a was mapped by a techniqueusing SPOTs peptides synthesized by Sigma Genosys (the Woodlands, Tex.).Overlapping peptides (12-mer) encompassing the entire human C5a weresynthesized on a cellulose membrane. In the assay, the membrane wasfirst treated with a blocking solution TBSTB (10 mM Tris chloride, 250mM sodium chloride, 1% bovine serum albumin and 0.05% TWEEN® 20) for 1hour at room temperature to saturate all the non-specific binding sites.MAb 136-26 at 1 μg/ml in the blocking solution was then added to themembrane for 1 hour at room temperature. The membrane was then washedthoroughly with a washing buffer TBST (10 mM Tris chloride, 250 mMsodium chloride and 0.05% TWEEN® 20). The membrane was then treated withHRP-conjugated goat anti-mouse IgG (Fc) antibody (diluted 1:5,000 in theblocking buffer) (Jackson Immunoresearch, West Grove, Pa.) for 1 hour atroom temperature. The membrane was then washed again. The binding ofMAb137-26 to the individual SPOTs peptides of C5a was detected byincubation with Supersignal West Pico chemilluminescent substrate(Pierce, Rockford, Ill.). The intensity of chemillumescence was thendetected by exposure to Kodak X-OMAT AR film (Rochester, N.Y.). FIG. 6shows the sequence of the epitope bound by MAb 137-26.

Example 5 An Ex Vivo Human Whole Blood Model for StudyingComplement-Mediated Inflammation: Effect of MAb137-26 on NeutrophilActivation by E. coli and on Killing of Neisseria meningitides

In order to investigate the role of complement in the complexinflammatory network, all potential cellular and fluid-phase mediatorsneed to be present and therefore are able to interact simultaneously.For devising such an experiment condition in vitro, human whole bloodwas used. In this model, lepirudin (REFLUDAN®), a thrombin specifichirudin analogue, was used as an anticoagulant instead of heparin.Unlike heparin, lepirudin does not interfere with complement activation.

In this model system, MAb 137-26 blocked the inflammatory effects of C5aformed as a result of complement activation by E. coli. The antibody didnot inhibit MAC-mediated killing of N. meningitidis. Therefore, MAb137-26 neutralizes C5a without inhibiting C5 activation and thesubsequent formation of MAC. This is an important feature of themonoclonal antibodies of the present invention.

Whole blood was collected in polypropylene tubes containing lepirudin(50 μg/ml). The anti-coagulated whole blood was pre-incubated with PBSor anti-C5 inhibitors for 4 minutes at 37° C. For the studies of CD11bexpression and oxidative burst on neutrophils, opsonized E. coli strainLE392 (ATCC 33572) was added to the whole blood samples for 10 minutesat 37° C. The E. coli concentration was 1×10⁷/ml blood in the CD11 bexperiments and 1×10⁸/ml in the oxidative burst experiments. The T−0baseline sample was processed immediately. After incubation, 100μ ofsamples was used for measurement of CD11b expression on neutrophils byimmunofluorocytometry. The oxidative burst of activated neutrophils wasmeasured using the substrate dihydrorhodamine 123 and performed asdescribed in the Burst-test procedure (ORPEGEN Pharma, Heidelberg,Germany).

FIGS. 7A-7D depict the results of the flow cytometric assays ofneutrophil activation for CD11b expression and oxidative burst.Anti-C5/C5a MAb137-26 inhibited effectively neutrophil activationinduced by E. coli in the human whole blood model of inflammation. Inthese assays, MAb137-26 is more potent than anti-C5a MAb561 (Dr. JurgKohl) and a peptidic C5aR antagonist (Dr. Stephen Taylor).

For the bactericidal assays, N. meningitidis H44/76-1 was grownovernight on BHI-agar, subcultured and grown into log-phase for 4 hours.5000-10000 colony forming units (CFUs) were added to 1.1 ml of lepirudinanti-coagulated whole blood samples preincubated for 5 minutes with PBSor antibody. At each time period, 100 μl of whole blood was seeded onmicrobiological Petri dishes containing blood agar and incubated for 24hours at 37° C. Bacterial growth was expressed as CFU/100 μl of wholeblood added. T−0 sample was obtained immediately after adding thebacteria.

FIG. 8 show that MAb137-26 did not inhibit MAC-mediated killing ofNeisseria meningitides. In contrast, MAb137-30 inhibited the killing ofNeisseria meningitides by human whole blood. This antibody inhibits C5activation.

It should be understood that the terms and expressions used in theforegoing sections are exemplary only and not limiting, and that thescope of the invention is defined only in the claims which follow, andincludes all equivalents of the subject matter of those claims.

1-17. (canceled)
 18. An isolated antibody or an antigen-binding fragmentthereof that binds to the same epitope of human C5 as the monoclonalantibody 137-26 produced from the hybridoma deposited with the ATCC anddesignated PTA-3650.
 19. The antibody or antigen binding fragmentthereof of claim 18, wherein the antibody or antigen-binding fragmentbinds to human C5 and C5a, but does not prevent the activation of C5 anddoes not prevent formation of or inhibit the activity of C5b.
 20. Theantibody or antigen binding fragment thereof of claim 18, wherein theantibody or antigen-binding fragment binds an epitope having the aminoacid sequence of EQRAARISLGPR.
 21. The antibody or antigen bindingfragment thereof of claim 18, wherein the antibody or theantigen-binding fragment thereof inhibits human neutrophil activationwith at least equal potency as the monoclonal antibody 137-26 producedfrom the hybridoma deposited with the ATCC and designated PTA-3650. 22.The antibody or antigen binding fragment of claim 21, wherein theinhibition of human neutrophil activation is determined by measuring theexpression of CD11b or the oxidative burst in neutrophils, induced byopsonized Escherichia coli in lepirudin-treated whole human blood. 23.The antibody or antigen binding fragment of claim 19, wherein theantibody or antigen-binding fragment binds to free human C5a with equalor better affinity than to human C5.
 24. The antibody or antigen bindingfragment of claim 19, wherein the antibody or antigen-binding fragmentinhibits the binding of human C5a to human C5a receptor.
 25. Theantibody or antigen binding fragment of claim 18, wherein the antibodyis a monoclonal antibody.
 26. The antibody or antigen binding fragmentthereof of claim 18, wherein the fragment is selected from the groupconsisting of Fab, F(ab′)₂, Fv, and single chain Fv.
 27. The antibody orantigen binding fragment thereof of claim 18, wherein the antibody is achimeric, deimmunized, humanized or a human antibody.
 28. The antibodyor antigen binding fragment thereof of claim 18, wherein the antibody orantigen binding fragment comprises a polymer that increases the halflife of circulation of the antibody.
 29. The antibody or antigen bindingfragment thereof of claim 18, wherein the polymer is polyethylene glycolhaving an average molecular weight between (i) 1,000 and 40,000; (ii)2,000 and 20,000; or (iii) 3,000 and 12,000.
 30. A pharmaceuticalcomposition comprising the antibody or fragment thereof according toclaim 18, and a pharmacologically acceptable carrier, excipient,stabilizer, or diluent.
 31. A method of inhibiting the activity of humanC5a comprising contacting human C5a with an antibody or antigen bindingfragment thereof, wherein the antibody or antigen binding fragment bindsto the same epitope on human C5 and human C5a as the monoclonal antibody137-26 produced by the hybridoma deposited with the ATCC and designatedPTA-3650.
 32. A method of treating a complement mediated disease orcondition comprising administering to a subject in need thereof anantibody or antigen binding fragment thereof, wherein the antibody orantigen binding fragment binds to the same epitope on human C5 and humanC5a as the monoclonal antibody 137-26 produced by the hybridomadeposited with the ATCC and designated PTA-3650.
 33. The method of claim31, wherein the antibody or antigen-binding fragment binds an epitopehaving the amino acid sequence of EQRAARISLGPR.
 34. The method of claim31, wherein the antibody or antigen binding fragment binds to free humanC5a with equal or better affinity than to human C5.
 35. The method ofclaim 31, wherein the antibody or antigen binding fragment inhibits thebinding of human C5a to human C5a receptor.
 36. The method of claim 31,wherein the antibody is a monoclonal antibody.
 37. The method of claim31, wherein the antibody is chimeric, deimmunized, or humanized, or ahuman antibody.